Ultra-high temperature burners



Feb. 14, 1967 EIICHI ISHIBASHI ULTRA-HIGH TEMPERATURE BURNERS Filed March 5, 1966 INVENTOR lSHlBASHI EHCHI 22 ATTORN United States Patent 3,303,645 ULTRA-HIGH TEMPERATURE BURNERS v Eiichi Ishibashi, Hitachi-shi, Japan, assignor to Hitachi, Ltd., Tokyo, Japan Filed Mar. 3, 1966, Ser. No. 531,582 Claims priority, application Japan, Apr. 30, 1963, 38/22,237 17 Claims. (Cl. 60-39.65)

This application is a continuation-in-part of an application to Eiichi Ishibashi for Ultra-High Temperature Burners, filed April 29, 1964, Serial No. 363,564, now abandoned.

The present invention relates to heat and pressure resistant wall structures, wherein the inner wall is not subjected to any substantial pressure differential and nozzle means are provided to direct cooling air across the inside surface of the inner wall, particularly tangentially and helically in the case of a cylindrical wall structure. More particuarly, the present invention relates to such a wall structure for use with ultra-high temperature burners in high temperature gas turbines for the generation of electricity.

In prior art gas turbine combustion chambers, it has been necessary to construct an inner wall to withstand temperatures of 2000 C. or higher. Usually cooling air has been introduced along the inner surface of the inner wall to protect this wall from the high temperatures. In general, the amount of cooling air required may be five to ten times the amount of air required for complete combustion of the fuel, so that the gas temperature is lowered to about 600-9()0 C., the required input gas temperature for a conventional gas turbine.

In ultra high temperature tunbine combustion chambers, air cannot be introduced in quantities normally tolerated in conventional high temperature burners, as mentioned above. In some cases, the gas temperature cannot be maintained high enough by the complete combustion of fuel with only air; therefore, oxygen is used to obtain extremely high gas temperatures, for example,

3000 C. Therefore, it is seen that high temperature burners can tolerate very little cooling air within the burner; thus, the conventional means of cooling an inner burner wall, as mentioned above, are not available for use in an ultar high temperature burner.

It is an object of the present invention to provide a wall structure suitable for use in ultra high temperature burners.

It is another object of the present invention to provide a wall structure that will introduce high velocity cooling air along the inner surface of the inner wall of a burner without subjecting the inner wall to any pressure differential. A further object of the present invention is to provide a cylindrical wall structure for an ultra high temperature burner that will introduce high velocity cooling fluid tangentially and helically along the inner surface of the inner wall, without subjecting the inner wall to any pressure differential.

Because substantial amounts of cooling air cannot be tolerated in a high temperature burner, the present invention employs a wall structure designed to introduce a relatively small amount of cooling air along the inside wall surface of the inner wall at the speed of sound or higher to obtain good heat transfer from the inside wall surface. However, in order to introduce cooling air along the inner surface of the inner wall at the speed of sound or higher, the cooling air must be placed under a pressure considerably higher than the pressure within the burner, for example, twice the pressure within the burner; accordingly, the inner wall structure is subjected to a large difierential pressure. For example, if the inner absolute pressure of the inner cylinder is 6 kg. per sq. cm., the

3,303,645 Patented Feb. 14, 1967 cooling air pressure outside the inner wall structure should be about 13 kg. per sq. cm.; therefore, the inner wall structure must be strong enough to withstand the differential pressure of 7 kg. per sq. cm. In addition, this inner wall structure is subjected to a very high temperature, because of the high temperature gases within the burner at around 3,000 C. Under such conditions, a conventional inner wall structure cannot have adequate mechanical strength to withstand such high temperatures and pressures, because high tempratures require a thin wall with low heating inertia and high pressures require a thick wall with high strength. In addition, present materials used to withstand high temperatures have a high thermal expansion, rendering thick walls undesirable. To solve these problems, .the present invention employs a thick intermediate wall to withstand the high pressures and a thin inner wall to withstand the high temperatures, which is apertured to eliminate any pressure differential, and nozzles to conduct and accelerate cooling fluid from outside the intermediate wall to the inside of the inner wall, without permitting the high pressure cooling fluid to first enter the space between the intermediate and inner walls. Preferably, these nozzles are constructed to introduce the cooling fluid tangential to the inner surface of the inner wall at or above the speed of sound, and to produce a helically moving layer of cooling fluid along the inner surface of a cylindrical inner wall. Preferably, this is accomplished by directing the outlet of the nozzles tangentially along the inner surface of the inner wall and arranging the nozzles circumferentially along the cylindrical inner wall in a helical pattern. In addition, the specific wall structure may employ a mount for the intermediate wall that allows radial thermal expansion, a rigid sealed connection between the nozzles and the intermediate wall, and nozzles designed at their inner end to concentrically support the inner wall without interfering with its radial or circumferential expansion while allowing fluid to freely pass between the nozzle and intermediate wall to eliminate any pressure differential across the intermediate wall.

Further objects, features, and advantages of the present invention will appear from the following specification in connection with the description of the accompanying drawing, in which:

FIGURE 1 is a longitudinal cross sectional view, with portions broken away, of a burner assembly embodying the wall structure of the present invention;

FIGURE 2 is a cross sectional view taken on line ]1--1I, of FIGURE 1, showing the specific nozzle structure of the present invention;

FIGURE 3 shows a modification of the nozzle 0 FIGURE 2;

FIGURE 4 is a view taken from line IV-IV, of FIG- URE 1; and

FIGURE 5 is a view taken from line VV of FIG- URE 1.

The burner assembly of FIGURE 1 comprises an outer cylindrical wall 1, an inner cylindrical wall 2, and a fuel nozzle 3, which are known per se. An anti-pressure intermediate cylindrical wall 4 is mounted between the inner and outer cylindrical walls 2 and 1, respectively.

A plurality of cooling air nozzles 5 are rigidly mounted to and sealed with respect to the intermediate cylindrical wall 4 by welding or other suitable means. The nozzles 5 have an inner portion of reduced size loosely extending within correspondingly formed openings in the inner cylindrical wall 2, to hold the cylindrical wall 2 concentric with respect to the walls 1 and 4. The intermediate wall 4 is suitably formed with openings leading into the nozzles 5 for conducting cooling air from a first annular passage between walls 1 and 4 to the interior of the burner, that is, within'inner wall 2. The cooling nozzles 5 are constructed to minimize aerodynamic losses and accelerate the high pressure cooling fluid; the nozzles are convergent or convergentdivergent, according to whether the cooling air velocity is to be lower than or higher than the speed of sound, respectively. The aerodynamically shaped nozzles result in less pressure loss than conventional orificetype passages and can be manufactured with high precision. I

The cooling air is introduced under high pressure in the first annular passage formed between walls 1 and 4; therefore, this first annular passage is filled with high pressure cooling air. From the first annular passage, the cooling air passes through nozzles 5 to increase in velocity and decrease in pressure, because of the aerodynamic shaping of the nozzles 5. After passing through the nozzles, the cooling air enters the relatively loW pressure space within cylindrical inner wall 2; thus, there is a relatively large pressure differential between the first annular passage and the space within cylindrical inner wall 2.

As mentioned above, it is desirable to construct the cylindrical inner wall 2 of a relatively thin sheet material to obtain desirable thermal inertia and thermal expansion characteristics. In addition, cylindrical inner wall 2 is constructed of a material having high temperature resistant characteristics, which is generally unsuitable to maintain a high pressure differential, that is, a large pressure difference between its opposite sides. However, as mentioned above, the inner portions of the nozzles 5 are loosely received in correspondingly shaped openings in the inner wall 2; therefore, a plurality of fluid passages are formed between the inner wall 2 and the nozzles 5, to substantially equalize the pressure on each side of the cylindrical inner wall 2. Therefore, at all times, the inzles 5 and the inner wall 2 allow for substantial radial and circumferential expansion of the wall 2, relative to the nozzles 5; this is necessary because high temperature resistant materials generally havea very large thermal coefficient of expansion.

FIGURE 2 illustrates the manner in which the cylindrical intermediate wall 4 is mounted with respect to the cylindrical outer wall 1, so that the intermediate wall may freely expand in the radial direction. Abutment means 6 and 7 are rigidly mounted on the intermediate cylindrical wall 4 and extend in the longitudinal direction. The abutment means 7 .slidingly engage the abutment means 8, which is rigidly mounted on the outer cylindrical Wall 1 and extends in the longitudinal direction. A longitudinally extending plate .12 is welded or otherwise rigidly secured to the intermediate cylinder 4 and slidingly interengages with two spaced parallel longitudinally extendmg plates 13, which are welded or otherwise rigidly secured to the outer cylindrical wall 1; these elements form interengaging means to concentrically mount the intermediate wall 4 and allow for its radial thermal expansion.

Thus, it is seen that the present invention provides a one piece cylindrical inner wallnecessarily constructed of costly heat resistant material-which may be constructed relatively thin to save on the cost of materials and construction. In addition, the thin wall structure has the advantage of a relatively small thermal inertia, which enables it to function satisfactorily during abrupt changes in load with accompanying abrupt changes in combustion gas temperature within the burner. Since highly heat resistant materials generally have a high thermal coefiicient of expansion, the thin wall construction is advantageous to materially reduce thermal stresses within the wall due to expansion. Another advantage of the present invention is that the relatively thick, strong, pressure resistant intermediate Wall 4 is shielded from direct contact with the hot combustion gases within the burner and shielded from the radiation of these gases by the inner wall 2; therefore, the intermediate wall .4 can be constructed primarily to resist pressure.

Experiments conducted with the wall structure of the present invention illustrate the manner in which the intermediate and outer walls are maintained at a minimum temperature. With a combustion gas temperature of approximately 1900 C. within the inner wall 2, the temperature of the inner wall 2 varied between 800 C. and 1000 C., while the temperature of the intermediate wall 4 varied between 400 C. and 600 C. and the temperature of the outer Wall 1 varied between 200 C. and 400 C. The advantages gained from the present invention are particularly apparent when it is realized that most known heat resistant materials have a sharp drop in' mechanical strength at temperatures above 600 C.

With reference to FIGURE 2, it is seen that the nozzles 5 will introduce the cooling fluid tangentially to the inner surface of the inner Wall 2. Thus, the high speed cooling fluid will be smoothly introduced into the burner along the inside surface of the inner wall, where its cooling effect is the greatest. The nozzles 5 are constructed to reduce the pressure of the cooling fluid to the pressure of the combustion gases within the burner. The nozzles 5 of FIGURE 2 are constructed as convergent nozzles to produce cooling fluid velocities up to the speed of sound. The modified nozzles 5a of FIGURE 3, are convergent-divergent nozzles designed to produce cooling fluid speeds in excess ofthe speed of sound. As shown in FIGURE 1, the nozzles 5 are circumferentially and axially spaced from one another, in a helical pattern. The nozzles are so arranged and designed in combination with the burner structure that the cooling fluid leaving the nozzles 5 proceed circumferentially around the inner surface of the inner wall 2 and axially with respect to the inner wall 2 toward the next nozzle .5 on the helical path. As the cooling fluid proceeds in this manner, its velocity and cooling effect decrease gradually until it reaches the next cooling nozzle-5, where additional cooling fluid enters at a high velocity, in the same direction, to maintain the cooling effect. The specific embodiments described have been set forth only for purposes, of illustration; therefore, numerous changes and modifications to those having ordinary skill in the art will be readily apparent and within the spirit and scope of the invention, as defined by the following claims.

' I claim:

1. A combustion chamber, comprising:

an outer first wall;

an inner second wall spaced from said outer wall;

an intermediate third wall spaced from said outer and inner Walls;

means, including said outer wall and said intermediate wall operable to contain coolingfluid under a high pressure in a first space, between said outer wall and said intermediate wall;

said intermediate wall and said inner wall being spaced from each other to form an intermediate space therebetween;

means, including said inner wall, enclosing a combustion space containing hot fluid on the inner side of said inner wall opposite from said intermediate Wall and said outer wall;

nozzle means operable to conduct cooling fluid from the first space, through said intermediate wall and into the combustion space, and operable to prevent the cooling fluid from entering the intermediate space before it enters the combustion space; said nozzle means being rigidly attached to said intermediate wall and extending toward and through a correspondingly shaped opening in said inner wall; said nozzle means having an inner portion of reduced size Within and smaller than the opening in said inner wall, an adjacent outer portion of increased size larger than the opening in said inner wall, and a shoulder portion transversely connecting said inner and outer portions closely adjacent to the outer side of said inner wall; said outer portion; said inner portion and said h l d I portion forming inner wall supporting means operable to allow free three-dimensional thermal expansion of said inner wall, and forming, with said inner wall, fluid passage means operable to conduct fluids between the inner and outer sides of said inner wall to prevent a differential pressure across said inner wall.

2. The device of claim 1, wherein said nozzle means is a convergent type nozzle constructed to direct the cooling fluid tangentially along the inner surface of said inner wall.

3. The device of claim 1, wherein said nozzle is a convergent-divergent type nozzle constructed to direct the cooling fluid tangentially along the inner surface of said inner wall.

4. The device of claim 1, wherein said inner, outer, and intermediate walls are cylindrical and concentric with respect to each other.

5. The device of claim 2, wherein said inner, outer, and intermediate walls are cylindrical and concentric with respect to each other.

6. The device of claim 3, wherein said inner, outer, and intermediate walls are cylindrical and concentric with respect to each other.

7. The device of claim 4, wherein said inner wall is continuous and integral throughout its axial length and circumference.

8. The device of claim 5, wherein said inner wall is continuous and integral throughout its axial length and circumference.

9. The device of claim 6, wherein said inner wall is continuous and integral throughout its axial length and circumference.

10. The device of claim 4, including a plurality of said nozzle means circumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only one circumferential direction.

11. The device of claim 5, including a plurality of said nozzle means circumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only One circumferential direction.

12. The device of claim 6, including a plurality of said nozzle means circumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only one circumferential direction.

13. The device of claim 7, including a plurality of said nozzle means ci-rcumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only one circumferential direction.

14. The device of claim 8, including a plurality of said nozzle means circumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only one circumferential direction.

15. The device of claim 9 including a plurality of said nozzle means circumferentially and axially spaced from each other in a helical pattern and operable to direct the cooling fluid in only one circumferential direction.

16. The device of claim 1, including means operable to mount said intermediate wall on said outer wall for relative radial, axial and circumferential expansion including an axially extending abutment bar rigidly mounted on said intermediate wall and a slidably engaging axially extending abutment bar rigidly mounted on said outer wall, and a plurality of slidably interdigitating axially extending bars rigidly mounted on said outer wall and said intermediate wall circumferentially spaced from said first mentioned abutment bars.

17. A combustion chamber, comprising:

an outer first cylindrical Wall;

an inner second cylindrical wall concentric with said first wall and continuous and integral throughout its axial length and circumference;

an intermediate third cylindrical wall concentric with said second wall and said first wall;

means, including said outer wall and said intermediate wall, operable to contain cooling fluid under high pressure in a first annular space, between said outer wall and said intermediate wall;

said intermediate wall and said inner wall being spaced from each other to form an intermediate annular space therebetween;

means, including said inner wall, operable to enclose a combustion space containing hot fluids contacting the inner surface of said inner wall;

nozzle means operable to inject the cooling fluid into the combustion space tangent to said inner wall, and operable to prevent the cooling fluid from entering the intermediate space before it enters the combustion space;

means to maintain the pressure within the combustion space equal to the pressure within the intermediate space;

means operable to mount said intermediate wall on said outer Wall for relative radial, axial and circumferential expansion including an axially extending abutment bar rigidly mounted on said intermediate wall and a slidably engaging axially extending abutment bar rigidly mounted on said outer wall, and a plurality of slidably interdigitating axially extending bars rigidly mounted on said outer wall and said intermediate wall circumferentially spaced from said first-mentioned abutment bars.

References Cited by the Examiner UNITED STATES PATENTS 12/1959 Jerie 49.65 1/1960 Haworth 6039.66 X 

1. A COMBUSTION CHAMBER, COMPRISING: AN AUTER FIRST WALL; AN INNER SECOND WALL SPACED FROM SAID OUTER WALL; AN INTERMEDIATE THIRD WALL SPACED FROM SAID OUTER AND INNER WALLS; MEANS, INCLUDING SAID OUTER WALL AND SAID INTERMEDIATE WALL OPERABLE TO CONTAIN COOLING FLUID UNDER A HIGH PRESSURE IN A FIRST SPACE, BETWEEN SAID OUTER WALL AND SAID INTERMEDIATE WALL; SAID INTERMEDIATE WALL AND SAID INNER WALL BEING SPACED FROM EACH OTHER TO FORM AN INTERMEDIATE SPACE THEREBETWEEN; MEANS, INCLUDING SAID INNER WALL, ENCLOSING A COMBUSTION SPACE CONTAINING HOT FLUID ON THE INNER SIDE OF SAID INNER WALL OPPOSITE FROM SAID INTERMEDIATE WALL AND SAID OUTER WALL; NOZZLE MEANS OPERABLE TO CONDUCT COOLING FLUID FROM THE FIRST SPACE, THROUGH SAID INTERMEDIATE WALL AND INTO THE COMBUSTION SPACE, AND OPERABLE TO PREVENT THE COOLING FLUID FROM ENTERING THE INTERMEDIATE SPACE BEFORE IT ENTERS THE COMBUSTION SPACE; SAID NOZZLE MEANS BEING RIGIDLY ATTACHED TO SAID INTERMEDIATE WALL AND EXTENDING TOWARD AND THROUGH A CORRESPONDINGLY SHAPED OPENING IN SAID INNER WALL; SAID NOZZLE MEANS HAVING AN INNER PORTION OF REDUCED SIZE WITHIN AND SMALLER THAN THE OPENING IN SAID INNER WALL, AN 